Multirange pump



Oct. 6, 1970 P. H. SCHEFFLER, JR.. ET AL 3,532,445

MULTIRANGE PUMP Filed Sept. 20, 1968 5 Sheets-Sheet 1 Oct. 6, 1970 P. H. SCHEFFLER, JR, ETAL MULTIRANGE PUMP 5 Sheets-Sheet 4.

Filed Sept. 20, 1968 FIG.|2."

MULTIRANGE PUMP 5 Sheets-Sheet 5 P. H. SCHEFFLER, JR. ET

Oct. 6, 1970 Filed Sept. 20, 1968 M 1.1 K IIIIIMIIII lzoA nited States Patent Oflice 3,532,445 Patented Oct. 6, 1970 3,532,445 MULTIRANGE PUMP Paul H. Scheiiler, Jr., Leonard J. Fox, Francis C. Stump,

and Carl M. Gauthier, Lima, Ohio, assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 20, 1968, Ser. No. 761,024 Int. Cl. F04d 1/00, 29/02; GZlb 7/14 US. Cl. 417-424 10 Claims ABSTRACT OF THE DISCLOSURE A pump for pumping molten metal, said pump having a rotor made from a limited number of easy to east, simple geometry, heat and corrosion resistant parts, a twopiece heat and corrosion resistant housing structure disposed about the rotor, clamping means for centering and securing the pieces together, a suspension system that substantially lowers a critical speed factor and limits low speed lateral movement of the rotor, and replaceable heat and corrosive resistant inlet and outlet structures which allow the pump to handle a wide range of flow rates.

BACKGROUND OF THE INVENTION The present invention relates to an improved pump for pumping liquid or molten metal.

In copending application Ser. No. 610,935, filed Jan. 23, 1966, by one of the present inventors, and assigned to the present assignee, is disclosed a pump structure capable of pumping and transferring liquid metal in an effective and efiicient manner. The disclosed pump comprises essentially a rotor and a housing made from a hard, heat and corrosion resistant or ceramic material, for example silicon carbide, and having two principal sections or stages, namely, an inlet or fiow control stage and a discharge stage. The housing for the discharge stage is a volute structure while the inlet housing comprises essentially a tubular or cylindrical shaped container having an open top end and a closed bottom end having an opening therein which functions as the inlet port to the pump.

In manufacturing and using such pumps, certain concerns and considerations are encountered. To provide an economical pump, the ceramic rotor and housing must first of all be cast or compacted which, in turn, requires component ceramic parts having simple geometric configurations. The simple geometry is further advantageous from a liquid flow standpoint since the viscosity and specific gravity of most molten metals are such that intricate flow paths substantially impede the flow of such metals.

Another concern involves the versatility of such pumps. In circulating and/or transferring molten metal, a single pump should be capable of handling different quantities of liquid metal in a specified period of time.

Other areas of concern involve that of securing and centering the volute and inlet housings together, and coupling the ceramic drive shaft to a metal drive shaft in a manner which compensates for characteristic expansion and contraction differences between the ceramic and metal with the temperature extremes encountered in molten metal environments. The high temperature extremes further require that the drive components including a drive motor and associated hardware be properly insulated.

The rotor of the pump described in the above-mentioned copending application is preferably fabricated from nitride bonded silicon carbide components. Because of the extreme hardness of this material, it is not practical to balance the rotor either statically or dynamically. This inherent rotor unbalance, together with a large overhang moment at the support bearings, will produce severe vibrational forces with the use of conventional suspension arrangements.

BRIEF SUMMARY OF INVENTION The present invention discloses structural arrangements which provide a highly effective, economical and versatile pump for pumping molten metals.

The pump comprises a rotor structure which includes an inner web and a tubular shaped housing disposed about and secured to the web to form internal rotor channels or passageways. The rotor is rotated by a drive shaft fixed within the rotor, and the rotor is enclosed by an outer housing, the housing, drive shaft and rotor components being made from a heat and corrosive resistant material such as nitride bonded silicon carbide.

The web and tubular housing, as well as the outer housing, are relatively simple geometric configurations which are thus easy to cast and which form a rotor structure that is rugged and strong, such characteristics being desirable and necessary when using devices made from brittle ceramic materials.

In a similar manner, the pump of the present invention is provided with replaceable inlet and outlet orifices having simple geometric configurations thereby easing the casting and assembling processes as well as providing a highly versatile pump, namely, a pump having a wide or extended range of liquid flow pumping rates.

The invention further includes a pump suspension system which provides good rotor stability with negligible transmission of vibrational forces to the pump housing and support structure. This is accomplished by mounting and securing the rotating assembly '(rotor, drive shaft and drive motor) at its extreme upper end to the pump housing through highly flexible devices, namely, elastomeric pads or bosses which carry the static load of the rotatable components in compression and the rotating loads in shear. This arrangement reduces the critical or naturally resonant speed of the rotating assembly to essentially that of an equivalent pendulum which is substantially below the operating speed of the pump. The lateral movement or excursion of the rotor, which occurs in passing through this critical speed (during starting and stopping), is readily restrained by snubbing the drive assembly through a loose fitting, energy absorbing structure disposed about the assembly.

To secure the rotor drive shaft to a metal drive shaft of the drive asembly, the invention provides a slotted, metal tubular element inserted into and expanded in a bore formed in the upper end of the rotor drive shaft. With the elevated temperatures encountered by the pump, the slotted element relaxes in the bore to limit the stresses imposed on the ceramic shaft yet maintains a necessary rigid connection and coupling over the pumps operating temperature range. Any off-center tolerance of the bore can be easily compensated for by machining the pilot end of the tubular element after it is inserted and expanded in the bore.

THE DRAWINGS The invention, along with its objectives and advantages, will best be understood from consideration of the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1A is a vertical sectional view of a pump suspension arrangement and the upper portion of a pump constructed in accordance with the principles of the present invention;

FIG. 1B is a vertical section of the lower portion of the pump shown in FIG. 1A;

FIG. 2 is a vertical sectional view (in partial elevation) of a pump rotor constructed in accordance with the principles of the invention;

FIG. 3 is a cross-ectional view of the rotor of FIG. 2 taken along lines III-III;

FIG. 4 is a top plan view of an inlet bushing forming a lower part of the rotor shown in FIG. 2;

FIG. 5 is a side elevation of the bushing shown in FIG. 4;

FIG. 6 is a top plan view of an impeller forming a portion of the rotor of FIG. 2;

FIG. 7 is a side elevation view (in partial section) of the impeller of FIG. 6 and an inner vane structure forming an upper portion of the rotor of FIGS. 1, 2 and 3.

FIG. 8 is a bottom plan view of the vane structure of FIG. 7;

FIG. 9 is a top plan view of an inner vane structure forming a lower portion of the rotor of FIGS. 1B, 2 and 3;

FIG. 10 is a side elevation view (in partial section) of the vane structure of FIG. 9;

FIG. 11 is a side elevation (in partial section) of an outer tubular structure forming part of the rotor shown in FIGS. 1 to 3;

FIG. 12 is a contracted, side elevation view of a shaft for driving the rotor of FIGS. 1 to 3; and

FIG. 13 is a shaft coupling means constructed in accordance with the principles of the invention.

PREFERRED EMBODIMENT Specifically in FIG. 1A, is shown the upper portion of a novel pump structure 10 and a novel suspension system 12 for suspending said pump in a vertical manner. The system supports a drive shaft 13, forming part of a drive assembly generally designated 14, and a drive motor 15 all flexibly suspended by a hanger assembly 18 supported on a rigid frame in a manner presently to be described.

A lower p ate 26 is provided with ports 27, and the drive motor 15 is preferably an air actuated motor provided with exhaust conduits 16 and 17 extending to portions of the drive assembly 14 for cooling same in a manner to be explained hereinafter. An air flow regulator R may be provided in the conduit 16 as shown.

The rigid frame 20 includes leg struts or bars 22 secured between upper and lower support plates 24 and 26 respectively, and intermediate upper and lower support members 28 and 30, respectively. The intermediate upper support member 28 is shown adjustably secured to the uppermost plate 24 by threaded bolts 29 which allow vertical adjustment or positioning of the assemblies and components supported therefrom. The lower intermediate support member 30 is suitably rigidly secured to the leg struts 22. In the uppermost plae 24 is secured an eye bolt 32 for attaching means (not shown) to the suspension system 12 for lowering and raising the system and the pump 10 suspended therefrom.

The hanger assembly 18 comprises U-shaped support brackets 34 resiliently secured to the upper intermediate support member 28 through elastomeric pads 36, and to an adapter support plate 38 for the motor 15 through suitable means such as threaded bolts as shown. The pads 36 are shown secured to the member 28 and the upper end of their respective brackets 34 by threaded bolts extending through the pads, the upper end of each bracket being disposed over the pads so that the weight of the components supported by the brackets is also supported by the pads.

The drive assembly 14 includes a coupling means 40 for coupling the shaft of the motor 15 to the drive shaft 13 in a shaft housing 41 extending between the motor plate 38 and a bearing housing 44 containing bearings for the shaft. The housing 41 is secured to the motor plate 38 by suitable bolts as shown, and the motor is supported on the plate, a lower portion of the motor extending through an opening 38A provided in the plate.

Attached to the bearing housing 44 is a stabilizing plate 45, the upper, circumferential surface of which is provided with a number of pads, or strips, of friction producing material 46, such as brake lining material, suitably fixed to said surface. In contact with the upper surface of the several strips is a loose fitting inertia plate 48 resiliently disposed in a horizontal overlapping plane parallel with the plate 45, the inertia plate being adjustably secured to the rigid member 30 by bolts 49. The resilient disposition of the plate 48 is provided by springs respectively provided on the bolts 49 between the heads thereof and the inertia plate. Further resiliency for the plate 48 may be provided by disposing an elastromeric spacer about each bolt 50 and in the holes shown in the plate 48 for accommodating the bolts.

The pump 10, as depicted in FIGS. 1A and 1B includes two principal sections or stages which are generally defined by two principal sections or stages which are generally defined by two principal housing portions, namely, an upper, volute housing cover and collector 52, and a lower elongated inlet housing structure 54.

The volute collector 52 is provided with an outlet port 56 for discharging liquid from the pump 10, said port support a replaceable discharge assembly comprising a pump adapter 57 and a pipe adapter 58, though the adapter 57 may be an integral part of the volute collector.

The inlet housing 54 is provided with a replaceable orifice structure 60 having an inlet orifice 61 for admitting liquid into the pump 10. The structure 60 is secured in the bottom wall portion of the inlet housing, as shown in FIG. 1B, the lower portion of the pump 10 and the orifice structure being shown submerged in a pool 62 of liquid to be pumped, though the invention is not limited to only submersible operation.

The volute and inlet housing portions 52 and 54 are further provided with flange portions 52A and 54A respectively which are disposed in abutting relation as shown in FIG. 1A. A suitable heat resistant cement or gasket 63 may be disposed between the flanges to seal the housing portions together.

In order to withstand the high temperature and corrosive environment of molten metals, the volute and inlet housing portions 52, 54 and the inlet orifice structure 60 are made from a hard, heat resistant material, for example, nitride bonded silicon carbide. The housing portions and inlet structure are thus preferably formed by casting or compacting processes. For this reason, the housing portions and inlet structure are provided with relatively simple geometric configurations which simplify and ease the casting operations and thereby reduce the cost of the pump 10 by reducing the cost of making the pump.

The pump 10 includes further a rotor 64 centraly disposed and vertically supported in the housing 52, 54, said rotor having an upper impeller portion 65 located in the volute housing 52 and a lower elongated inlet portion 66 extending into the inlet housing 54 and over the inlet orifice 61. The rotor is comprised essentially of five, separately fabricated parts, namely, upper and lower inner web portions 68 and 70 respectively, an outer tubular housing 71 surrounding and secured to the Web portions, an inlet bushing 72 secured to the bottom end of the lower web 70 and tubular housing 71, and a drive shaft (to be described hereinafter) in a manner and for purposes presently to be explained.

The rotor components are shown in separate detail in FIGS. 3 through 12, and, like the housing portions 52 and 54 are preferably cast or compacted from a heat and corrosive resistant material such as silicon carbide. For this reason, the geometries of the rotor components are kept as simple as possible as seen in the figures.

As seen in the cross-sectional and plan views of FIGS. 3, 8 and 9, the upper and lower web structures 68 and 70 have vane portions 75 extending in an outwardly radial direction, said vanes forming longitudinally extending passageways or channels 76 (FIGS. 1B and 2) when the web structures are secured together in an end to end manner.

As best seen in FIG. 7, the upper ends of the vanes 75 of the upper web 68 are formed to project in a radially outward and upward direction to form the impeller 65 as an integral part of the rotor 64. FIG. 6 shows a top plan view of the impeller vanes.

The lower end of the web 68 is shown provided with alternately spaced bosses and recesses 79 and 80 (FIG. 7), respectively, for mating engagement with the upper end of the web 70 which is similarly provided with alternately spaced bosses and recesses 81 and 82 (FIG. Thus, the vanes 75 of the two webs are aligned by proper mating of said bosses and recesses when the web ends are placed together. The Webs are secured together to form an elongated unitary web structure by use of a suitable cement 84 (FIG. 2) disposed between the mating bossed-recessed surfaces, and fired to form a strong, heat and corrosive resistant bond between said surfaces. The cement 84 is preferably a silicon carbide cement.

The unitary web structure 68, 70 is next disposed in the tube 71, the tube and web being dimensioned so that the outwardly facing surfaces of the vanes 75 engage or are located closely adjacent the inner surface of the tube. The web is then secured in the tube by a heat resistant cement 85 (FIGS. 2 and 3) disposed and retained in indentations 86 provided in the outward facing faces of the vanes which preferably extend the length thereof, and between the contacting or adjacent surfaces of the vanes and tube. The cement 85 is fired to form strong, heat resistant bond like that of 84.

As shown in FIG. 2, the length of the combined webs 68 and 70 is such that with the impeller vanes 65 located at the immediate top of the tube 71, a space is left in the bottom of the tube to accommodate the inlet bushing 72.

The inlet bushing 72 is provided with radially projecting vanes 88 (FIG. 4) which extend axially of the bushing (FIG. 5) between a lower flange portion 89 and the top of the bushing to form axially extending channels 90 and narrow vertical wall portions 91 (FIG. 2). The vertical wall portions are provided with openings 92 for admitting liquid into the rotor. The top of the bushing is provided with bosses 93 and recesses 94 which are formed and dimensioned to respectively engage corresponding recesses 95 and bosses 96 provided on the lower end of the web 70 as shown in FIG. 10. 'In a similar manner, the upper surface of the bushing flange 89, and the lower end of the tube 71 are provided respectively with bosses and recesses 97 and 97A, and 98 and 98A as shown in FIGS. 5 and 11, respectively.

To complete the lower end of the rotor 54, the bushing 72 is inserted into the lower end of the tube 71 (FIG. 2), the upper surface of the bushing flange 89 engaging the bottom surface of the tube. A heat resistant cement 99 is disposed (and fired like that of 84 and 85) between said surfaces and between the outwardly facing surfaces of the vanes 88 and the inner surfaces of the tube 71, as indicated in FIG. 2, for securing the bushing in the end of the tube. The bosses 93 and 97, and recesses 94 and 97A of the bushing are positioned (i.e., rotated) to respectively engage the recesses 95 and bosses 96 of the web 70, and the recesses 98A and bosses 98 of the tube 71, in a manner to locate the channels 90 of the bushing in alignment with the elongated channels 76 of the unitary web structure 68, 70 as shown in FIGS. 1B and 2.

The bushing 72 forms an inlet opening 100 (FIG. 2) to the rotor 64, and is adapted to secure a removable inlet orifice structure 101 having an inlet orifice 102 as shown in FIG. 1B. As shown, the orifice structure may be secured in the bushing by oppositely disposed pin means 103, the pins and orifice structure being made from heat resistant materials, preferably silicon carbide. The pins are disposed in holes cast in the bushing and secured therein by a suitable heat and corrosive resistant cement. To accommodate the pins in the orifice structure, the structure may be provided with respective grooves cast therein which extend to the periphery of the structure, the structure being inserted in the opening in a direction perpendicular to the direction of its normal position. A small amount of cement is added to each groove or pin (or both) to secure the orifice structure against rotation after the cement hardens.

Both inlet orifice structures 60 and 101 may be respectively retained in the housing 54 and bushing 72 in the manner described above or in any other manner suitable for removing and replacing the structures to allow the pump 10 to handle different liquid flow rates and thereby provide the pump with a wide or multirange characteristic when the discharge assembly, comprising the pump and pipe adapters 57 and 58, is similarly changed.

To drive the rotor 64, an elongated drive shaft 105 extends through a central opening 104 provided in the top of volute housing 52, and extends through a central opening 107 provided in the webs 68 and 70'. The upper end of the opening 104 is partially closed by an insulating cap 106 suitably secured to the top of the volute housing.

The lower end of the drive shaft 105 is provided with an outwardly extending peripheral flange 108 which engages the underside of an inwardly extending flange 109 provided at the top of the inlet bushing 72 as best seen in FIGS. 1B and 2. A side elevation view of the drive shaft is shown in FIG. 12.

Like the mutually engaging end surfaces of the webs 68, 70 and the inlet bushing 72, the engaging surfaces of the flange portions 109 and 108 of the bushing 72 and shaft 105 respectively may be provided with interlocking bosses and recesses (see FIGS. 5 and 12) to insure positive engagement for driving purposes, the interlocking surfaces being further coated with a suitable heat resistant cement 110 (FIG. 2) to secure the two members together.

In a similar manner, the shaft 105 may be secured to the Web portions 68 and 70 by cement 112. disposed between the outer surface of the shaft and the inner surface of webs formed by the central opening 107 as indicated in FIGS. 2 and 3.

If the shaft 105 is a hollow structure as shown, a plug means 114 is disposed and cemented in the lower end of the shaft to prevent liquid from flowing into the shaft. Like the other pump components, the shaft and plug are preferably made from silicon carbide or other suitable heat resistant materials.

The curing and hardening of the cement to secure the components, as individually described above, may be accomplished at one time by simply heat treating the pump 10 as a unit after the cement is applied and the components assembled.

In order to provide a rigid coupling between the metal shaft 13 and the hard, more brittle shaft 105 over the entire operating temperature range of the pump 10 without placing undue stress on the shaft 105, a slotted tubular, coupling device or member 116 is disposed and fixed in the upper end of the shaft 105, and is secured to the metal shaft 13 by way of cooperating flanges 117 and 118 re spectively provided adjacent the ends of shaft 13 and the coupling device 116.

An enlarged view of the coupling device 116 is shown in FIG. 13 before it is disposed and fixed in the end of the shaft 105. As shown in the figure, the wall of the device 116 is provided with two rows of angularly disposed, circumferentially spaced slots 120, the rows being axially spaced apart so that they are located towards the upper and lower ends of device.

The slotted device 116 is next disposed in a bore 121 provided in the upper end of the shaft 105 to a location where the top row of the slots 120 is located at least partially below the top of the shaft. The wall of the slotted device in the area 120A of the slots is next expanded by an appropriate tool (not shown) to tightly engage the inner surface of the shaft formed by the bore 121 as shown in FIG. 1A. To secure the cupling against rotation within the bore, a suitable pin means 122 is disposed to extend between opposed openings 123 in the shaft and opposed openings 124 in the coupling device.

The slots 120 of the coupling device 116 are dimensioned to allow relaxation of the expanded wall portions 120A at high temperatures so that the coupled end of the shaft 105 will not be unduly stressed with the expansion of the coupling device, the shaft being made of a heat resistant material which is brittle. With low temperatures, the expanded portions 120A maintain rigid engagement in the bore 121 of the shaft.

The coupling 116 has a further advantage, namely, the advantage of being sized to accommodate a wide range of bore tolerances in the shaft 105. The shaft bore 121, into which the coupling 116 is inserted and fixed, is formed by a core element (not shown) inserted into the mold for casting the shaft. Consequently, the location and diameter of the bore 121 will vary from piece to pice, and heretofore, this variation in tolerance could be eliminated only by very costly internal grinding of the extremely hard shaft materials by diamond grinding wheels.

The coupling 116 of the present invention eliminates this problem and cost by simply machining the upper end of the coupling, after it is installed in the shaft 105, to be concentric with the outer diameter of the rotor 64 thereby compensating entirely for the out-of-location tolerance of the cored bore 121.

To secure the volute and inlet housing portions 52 and 54 together, and to center and secure the pump to the suspension system 12, a clamping assembly 130 is provided comprising essentially a vertical wall structure 131 having an inwardly extending lower wall or flange portion 132, engaging the lower or base plate 26 described above in connection with the suspension system 12. As shown in FIG. 1A, the vertical wall 131 is attached to the plate 26 by bolts threaded into a wide or flange portion 133 provided at the top top of the wall.

The clamping assembly 130 includes further a ring 135 made of a heat resistant material and a metal ring 136 disposed on and resiliently pressed against 135 by springs 13*8 held in a vertical position by bolts 139 threaded through the base plate 26. In this manner, the volute housing 52 is forced down against the flange 54A of the inlet housing 54.

The flange 54A is supported by the clamping assembly 130 by its engagement with a heat resistant horizontal ring 142 which is supported by a heat resistant vertical ring 141. The ring 141 is secured to the vertical wall structure 131 by a number of tangentially disposed struts 143. Contact between the flange 54A and the horizontal ring 142 is made by a heat resistant gasket 142A cemented to the underside of flange 54A. The loss of heat from the flange is minimized by an insulation baffle 132 which is suitably secured to clamping assembly 130 in close proximity to flange 54A, for example, by vertically disposed studs (not shown) welded to the tangential struts 143. In this manner, the springs 138 and the horizontal ring 142, supported by ring 141, maintain the volute and inlet housings together without undue stresses being imposed on the housings which are made from brittle, heat resistant materials as explained above.

As further shown in FIG. 1A, the structure 131 is provided with an opening 145 to accommodate the pump discharge assembly 57 and 58.

A generous quantity of thermal insulation 148 is disposed between the external surfaces of the volute housing 52 and housing flanges, 52A, 54A and the interior surfaces of the clamping assembly 130 under the bottom surface of the plate 26. This insulation, and the insulating cap 106, serve to minimize the loss of heat from the molten metal to the drive components located above the plate 26, and maintain a uniform temperature level above the freezing temperature of the molten metal being pumped within the pump structures 52, 57 and 58.

In operation, the pump 10 may be lowered into a vessel or other means (not shown) containing the liquid to be pumped by appropriate means (not shown) attached to the eye bolt 32 secured in the top plate 24 of the suspension system 12. Only the inlet portion 54 of the pump, however, is submerged in the liquid.

The motor 15 is energized to effect rotation of the pump rotor 64, thereby effecting pumping action in the manner described in the above-mentioned copending application. That is, the liquid to be pumped, for example the liquid 62 in FIG. 1B, is drawn into the pump and rotor through the inlet orifices 61 and 102 by virtue of aforced vortex of liquid being produced in the rotor as it rotates. As shown by appropriate arrows in FIG. 1B, the liquid enters the channels and 76 between the vanes 88 and 75 of the rotor through the openings 92 in the inlet bushing 72. The liquid flows up through the channels and past the impeller vanes 65 in the volute collector 52. The impeller functions to increase the pumping head developed in the inlet portion 54 of the pump, and imparts a tangential velocity component to the liquid. The volute collector converts the tangential velocity component to a linear flow for direction and discharge through the outlet opening 56 and the discharge assembly 57, '58.

Pressurized air (or other actuating fluid) is directed to the motor 15 by a suitable conduit (not shown) to energize the motor and thereby effect rotation of the rotating components of the pump 10. The air exhausts from the motor through the conduit 16 and regulator R, said conduit directing air about the drive components to cool said components including the bearing 44. A lesser amount of air is directed to the coupling flanges 117 and 118 by the conduit 17 (said conduit having a somewhat smaller diameter than that of conduit 16) to cool the coupling shaft member 116. The cooling air exhausts from the area of the drive components through the ports 27 provided in the base plate 26.

As explained earlier, and as evident from the draw-- ings and figures, the pump structure 10 provides relatively simple flow paths for a high viscosity liquid such as molten metal, and the pump components have simple geometries for simplifying the casting or compacting processes and thereby lowering the cost of the pump.

As explained above, the flow rate pumping range of the pump 10 can be greatly extended by use of the replaceable outlet and inlet orifice structures 57, 58, 60 and 101. For example, in pumping molten aluminum at approximotely 1400 F., the pump can pump at rates starting at 10,000 pounds per hour to 400,000 pounds of aluminum per hour.

Because of the extreme hardness of the material of the rotor 64, the rotor cannot be economicaly balanced either statically or dynamically. With conventional, prior art suspension arrangements, rotor unbalance, together with its large overhang moment at the support bearings 44, would produce and transmit severe vibrational forces to the pump housing and support structure.

With the suspension system 12 of the present invention, good rotor stability is obtained with negligible transmission of vibrational forces to the pump housing 52, 54 and the rigid support structure 20. This is accomplished with the resilient support pads 36 in the following manner.

As evident from FIG.'1A, the combined weight of the rotor 64, the drive shaft 105, the drive assembly 14 and the motor 15 is supported by the resilient pads 36 mounted at the extreme upper end of the suspension system 12. This allows optimum flexibility and since the pads carry the static load of the rotor and drive components in compression and the dynamic or rotating load in shear. In this manner, the inherent resonant speed of the rotating assembly is reduced to that of an equivalent pendulum which is very much below the operating speed of the pump 10. The lateral excursion of the rotor in passing through this resonant speed,'during stopping and starting periods, is readily restrained by snubbing the drive assembly 14 through the use of the loose fitting inertia plate 48 acting on the plate 45 (and the friction material 9 46) attached to the drive assembly. The friction material absorbs energy and thereby dampens lateral movement of the rotating components by allowing some slippage between said components and rigid frame 20.

A metal, truncated cone structure 150 is secured between the base plate 26 and the uppermost plate 24. The function of the cone is to direct the air flow exhausted from the drive motor 15 over the drive system components and thus promote cooling in the manner explained above. The cone 150 further acts as a shield to minimize contamination of the drive system components by atmospheric dirt and dust.

An insulating chamber, which is not a functional part of the pump assembly, but aids in its installation and removal, is provided in the form of an insulating cylinder 151 reinforced by a metal cover 152. With the pump 10 installed as shown in FIG. 1A, the insulating chamber will surround the drive system components and shield them from heat radiated from such sources as furnace structures which are likely to be in close proximity to the pump. When the pump is withdrawn from the molten metal, the lower portions (54, 60, 66) of the pump will be drawn up into this chamber so that an upper flange 153 of the cylinder will engage the base plate 26. The axial length of the chamber is such that in the withdrawn position of the pump, the insulating chamber will enclose all of the pump surfaces that are normally immersed in the molten metal 62, thus allowing these components to cool slowly and uniformly. 'In addition, the chamber serves as a shield to prevent personnel contact with the hot pump surfaces.

It should now be apparent from the foregoing description that a new and useful pump 10 and pump suspension system 12 have been disclosed for pumping highly corrosive liquids, such as molten metal, in an unobvious and highly effective manner. More particularly, the pump is provided with removable and replaceable outlet and inlet orifice structures 57, 58, 60 and 101 which greatly extend the flow rate range of the pump; the rotor and drive assembly of the pump are resiliently supported by a hanger arrangement 18 which transmits little or no vibration to the pump housing and support structure; the hard, heat resistant drive shaft 105 is further easily centered with the rotor OD and coupled to the metal shaft 13 by way of the slotted tubular coupling member 116 which allows machining of its exposed end and provides rigid engagement with the shaft 105 without placing undue stresses thereon at high temperature values; the geometric configurations of the pump components are simple and few in number thereby providing simple flow paths for highly corrosive and viscous liquids, and ease of casting or compacting in making the components.

Though the invention has been described with a certain degree of particularity it should be understood that changes can be made therein without departing from the spirit and scope thereof.

What is claimed is:

1. In a pump structure for pumping and transferring liquids,

an elongated rotor comprising,

an elongated inner web structure and an elongated outer tubular structure disposed about said web structure and secured thereto, said web and tubular structures forming relatively straight passageways extending axially of said rotor for directing the liquid to be pumped therethrough said rotor having an inlet bushing secured to an end thereof with openings provided in said bushing and disposed in fluid communication with said passageways, said bushing being adapted to hold a first removably secured orifice structure, said structure having an opening therein which forms the inlet orifice of rotor,

shaft means secured to said web for rotating said rotor,

and

a housing structure disposed about said rotor, said housing having a bottom wall, and a second inlet orifice structure removably secured in said bottom wall with an inlet orifice disposed in fluid communication with said rotor inlet orifice and said passageways, and said housing also having an outlet port communicating with said passageways remote from said rotor inlet bushing discharge assembly replaceably secured to said housing with an outlet orifice in fluid communication with said outlet port,

said rotor, shaft and housing being made from. a hard,

heat and corrosive resistant material.

2. The structure described in claim 1 in which one end of the web structure includes an impeller structure extending beyond the end of the tubular structure,

the housing structure including a volute housing disposed about said impeller structure and an inlet housing disposed about the remainder of the rotor, and

clamping means for centering and securing said volute and inlet housings together.

3. The structure described in claim 1 in which the housing structure includes a volute housing and an inlet housing, said inlet housing having an outwardly extending flange portion adjacent one end thereof,

clamping means for securing the volute and inlet housings together, said clamping means including a base plate disposed over said volute housing,

a flanged structure disposed beneath said plate and about said volute housing, and

means for securing the plate and flanged structure to gether,

the flange of said structure extending inwardly to engage the underside of the flange portion of said inlet housing.

4. The structure described in claimv 1 in which at least one end of the drive shaft is provided 'with a bore extending axially of the shaft, and

a metal tubular coupling member disposed in said bore, said member being provided with slotted portions,

said slotted portions engaging the inside surface of the bore to form a rigid coupling therewith over the operating temperature range of the pump, said slotted portions being further effective to limit the stresses imposed on the shaft.

5. The structure recited in claim 1 in which the volute housing has an outlet port,

a ceramic discharge assembly physically associated with the volute housing and disposed in fluid communication with said outlet port, said assembly compris- 111g,

pump adapter means physically connected to the housingadjacent said port and in fluid communication therewith, and

pipe adapter means physically connected to said pump adapter,

said pipe adapter providing means for connecting an external conduit to said discharge assembly.

6. The structure described in claim 1 in which the material of the rotor, shaft and housing is nitride bonded silicon carbide.

7. A system for suspending a pump having a housing, a rotor and a shaft for driving said rotor, said system comprising a rigid frame structure attached to the pump housing, said frame including a base plate and an upper plate vertically separated and secured together by an elongated rigid structure extending therebetween,

a hanger assembly resiliently attached to and disposed below said upper plate, said assembly including elastomeric pads secured between the rigid frame and said hanger assembly,

said hanger assembly being further attached to the rotor drive shaft, and

said hanger assembly, including said elastomeric pads,

supporting the weight of said rotor and shaft.

8. A vibration dampening arrangement for a pump having a housing, said arrangement including a rigid frame structure attached to said housing,

a hanger assembly resiliently attached to said rigid frame,

a loose fitting inertia plate resiliently attached to said rigid frame,

a stabilizing plate rigidly attached to said hanger assembly, said plates having overlapping portions disposed in parallel planes, and

a friction material fixed to at least one of said plates in the area of the overlapping planes,

said friction material disposed to engage the other of said plates.

9. A drive assembly for rotating a pump rotor having an internal web structure and a shaft secured to said web structure, the drive assembly comprising a drive motor, I

a metal drive shaft extending between said motor and said shaft secured to said web structure,

means for coupling said metal shaft to said shaft secured to said web, and

bearings supporting said metal shaft for rotation.

12 10. The structure described in claim 9 in which the drive motor is actuated by pressurized fluid,

means for exhausting said fluid in the area of the drive assembly, said fluid being effective to cool the drive assembly.

References Cited UNITED STATES PATENTS 678,223 7/1901 Christian 103-114 786,922 4/1905 Smith 10 3114 2,528,210 10/1950 Stewart 103-114 3,336,875 8/1967 Conhagen 10388 FOREIGN PATENTS 454,709 2/1950 Italy.

HENRY F. =RADUAZO, Primary Examiner US. Cl. XJR. 

